Borehole fluid telemetry systems, generally referred to as mud pulse systems, serve to transmit information from the bottom of a borehole to the surface during drilling operations. For purposes of the present disclosure, all fluids that might be used in a well during the course of a drilling operation are referred to herein as “drilling fluid.” Virtually any type of data that may be collected downhole can be communicated to the surface through use of mud pulses telemetry systems, including information about the drilling operation or conditions, as well as logging data relating to the formations surrounding the well. Information about drilling operations or conditions may include, for example, pressure, temperature, direction and/or deviation of the wellbore, and drill bit condition; and formation data may include, by way of an incomplete list of examples, sonic density, porosity, induction, and pressure gradients of the formation. The transmission of this information is important for control and monitoring of drilling operations, as well as for diagnostic purposes.
The data pulses may be produced by a valve arrangement alternately obstructing and opening a drilling fluid conduit provided by the drill string. Mechanisms employed in the actuation of such valve arrangements are subject to substantial wear, while a rate of data pulse production, and therefore of transmission bandwidth, may be limited by force application capabilities of an actuating mechanism that actuates the valve arrangement.